It's not so much that they may ask you to reference a specific question-i don't think they have ever done that, it's simply 'one text from the stimulus booklet'. It's more a problem that they MAY ask you to reference two, or you may be studying a text that you just can't make relevent to the question, so it's good to look at a few for varied perspectives and approaches to the journey concept.
good luck with your exams!